Southwest Airlines, which carries more domestic passengers than any other U.S. airline, will become the latest to stuff more seats into its aircraft so it can sell more tickets on each flight.

Southwest is redoing the interiors of its jets, replacing the seat cushions with thinner foam materials while keeping most of the same frames and swapping out bulky seat-back pockets for mesh. The thinner cushions are actually more comfortable, Southwest says, and even though the airline is adding one more row of seats to its Boeing 737s, passengers will get the same usable space. Seat pitch – the space allotted to each row, including the seat and legroom, — will drop to 31 inches from 32 inches.

Slim seats can be comfortable and beneficial for both airlines and passengers, as this story from Lufthansa showed. With slimmer seat cushions, airlines have a choice of whether to leave the same number of seats on planes and give the extra space not taken up by thicker cushions to passengers, or whether to keep the extra space for the airline by stuffing in more rows. Most airlines, needing to bolster their finances, opt for more seats over more space. Southwest 737-700s will go to 143 seats from 137 seats.

Southwest said it is also reducing the amount of recline in its seats to just two inches of travel at the top of the seat from three inches. That’s a change many travelers welcome …